Mold plug for forming slab casting



Sept. 5, 1967 I GRUBER 3,339,879

MOLD PLUG FOR FORMING SLAB CASTING Filed Sept. 14, 1964 l5 I I 'IIIIIIIILIA Lou/s v GEUBEQ INVENTOQ ATTORNEY S United States Patent M 3,339,879 MOLD PLUG FOR FORMING SLAB CASTING 1 Louis Gruber, 4382 Bakman, North Hollywood,

Calif. 91602 Filed Sept. 14, 1964, Ser. No. 396,205 4 Claims. (Cl. 249-177) This invention has to do generally with the casting or molding of slabs of artificial stone or the like and particularly with a mold plug or core for use in providing a relative large opening in a cast slab such as required for a bathroom lavatory top or the like.

An object of the invention is to provide a simple, relatively inexpensive, novel device in the nature of a mold plug or core for use in the casting of slab-like bodies of artificial stone with large apertures therein.

Heretofore, due in part to the shrinkage which takes place in the artificial stone castings and in part to the construction of the cores, it has been necessary to leave the core member or plug in place for many hours after the casting is poured. Another object of the invention, therefore, is to provide a new and improved construction for a mold plug or core which enables the plug to be removed from the casting in a relatively short time after the material has been cast, thereby allowing the early reuse of the mold plug and reducing the cost of the cast article.

Another object is to provide a device of the type indicated which embodies a demountable flexible peripheral band which enables the removal of the main body of the device from a casting.

Still another object is to provide a device of the type indicated which is provided with means for releasably securing it to the mold at any desired place.

A further object of the invention is to provide a new and improved self-holding bar for use in a mold as a partition or end wall therefor.

These and other objects will be apparent from the drawings and the following description. Referring to the drawings:

FIG. 1 is an isometric view of a mold and casting, the latter partially broken away, showing elements embodying the invention;

FIG. 2 is a sectional view on line 2-2 of FIG. 1 but on a larger scale, showing the mold plug device of the invention;

FIG. 3 is a plan view of the mold plug;

FIG. 4 is an isometric view of a mold bar shown from the underside;

FIG. 5 is a fragmentary sectional view on line 5-5 of FIG. 1 but on a larger scale;

FIG. 6 is an edge view, partly in section, of another form of mold plug; and

FIG. 7 is a fragmentary cross-sectional view of a modified form of the mold plug of FIGS. 1-3.

More particularly describing the invention, reference numeral 11 generally indicates a mold for use in casting or molding slabs of artificial stone, such as artificial marble. The mold has a bottom wall 12, the upper surface 13 of which is polished smooth, and two side walls 14. Normally the mold 11 is made considerably longer than the average slab to be cast so that in many cases two or more slabs can be cast simultaneously in the mold by the use of bars 15 between the side walls 14 which serve as end walls and as partition walls as will be seen in FIG. 1 where three such bars are shown forming the two cavities 16 and 17. In FIG. 1 numeral 18 designates the cast stone.

In each mold cavity I show a mold plug 20 embodying the invention and this comprises a body 21 of plate-like form which may be made of wood, metal, plastic or other 3,339,879 Patented Sept. 5, 1967 suitable material. The body is shaped to provide a peripheral surface 22 having the contour or shape of the opening which is to be formed in the casting. I prefer to form the body with a rabbeted edge, that is, the surface 22 is recessed with respect to a downwardly facing shoulder 24 on a flange-like portion 25 of the body. A feature of the invention is the provision of a demountable or removable band 26 on the body 21 which fits slideably on the surface 22 and abuts the shoulder 24. This band may be made of polyethylene or some other suitable plastics.

Another feature of the mold plug is the provision of means for anchoring the device in place at the desired point in the mold and to accomplish this I show the body 21 provided with two suction cups 30. These are, in each case, mounted on a pin 31 which extends through an oversize opening 32 in the body and is provided with a head or knob 34 above the upper surface 35 of the body.

-With the construction described, one or more of the mold plugs is mounted at the appropriate place on the surface 13 of the mold and secured thereby depressing the pins 31 to actuate the suction cups into holding engagement with the surface of the mold. The mold plug is particularly designed for use in casting artificial stone simulating marble in which a polyester resin is combined with silica or limestone fillers or a mixture of these, and a suitable catalyst. A feature of the invention lies in the use of the band 26 on the body 21 of the plug. With this construction the body of the plug can be removed from the mold within a few minutes after the casting has been poured, leaving the band in place. This has not heretofore been possible with other types of plugs due to the shrinkage of the cast material. In removing the plug the two knobs 34 may be used to forcibly break the vacuum of the suction cups one at a time and to lift the mold plug body.

As previously indicated, special bars 15 are used to divide the mold into sections and to form end walls therefor. Heretofore, metal bars used for this purpose have had to be firmly anchored by clamps, and, in many cases, some material would flash or flow under the bars. To overcome these disadvantages of the metal bars, I provide a bar which is formed of a relatively stifl, yet somewhat flexible material, such as polyethylene. The bar is formed to provide an interior hollow space or recess 37 which is open on the underside of the bar, and preferably the bar is so designed as to provide a sharpedged wall section 38 at the mouth of the recess whereby the bar can be anchored in place in the mold by suction.

In FIG. 6 I show another form of mold plug, designated 20A, wherein I provide a body 40 formed of a suitable plastics or the like, such as polyethylene. The body has a flat, plate-like main wall or section 41 and a downwardly projecting peripheral wall or flange 42 which terminates in a sharp or thin edge 43. The main wall 41 is provided with a fitting 45 including a valve 46. With this construction the entire device can be anchored in place as a large vacuum cap. For example, with the valve 46 open, the main wall 41 of the plug may be pressed firmly toward the mold and the valve then closed. At the same time the peripheral wall curves outwardly at its edge to provide a similarly curved surface defining a portion of the wall of the opening in the completed casting.

In FIG. 7 I show amodification of the form of the invention shown in FIGS. l-3. Numeral 20B designates a device generally similar to the device 20 and including a plate-like body 213 having a rabbeted periphery including the recessed surface 22B and the shoulder 24B. The body may be made of Formica or other suitable material. I provide a band 29B of polyethylene plastic or other suitable material which is rabbeted at its upper edge 50 to substantially fit the periphery of the body as shown. The lower edge is preferably tapered at 51 to cause it to curve outwardly when the device is seated in the mold.

Although I have illustrated and described a preferred form of my invention, I contemplate that various changes and modification can be made therein without departing from the invention, the scope of which is indicated by the following claims.

I claim:

1. A mold plug for use in forming a relatively large opening in a slab casting of artificial stone or the like, comprising a plate-like body having a peripheral surface substantially conforming in contour to the opening desired to be formed in the casting, and means for detachably fastening said body to the wall of a mold including at least one resilient suction cup on the bottom side of said body, and an element extending through said body from top to bottom and being movable relative to the body and supporting said cup at its lower end.

2. A mold plug for use in forming a relatively large opening in a slab casting of artificial stone or the like, comprising a plate-like body having a peripheral surface substantially conforming in contour to the opening desired to be formed in the casting, and having means forming a downwardly facing shoulder at the upper end of said surface, a flexible band removably mounted on said surface, a suction cup beneath said body, and an element extending through said body from bottom to top, said element being movable relative to the body and supporting said cup at its lower end.

3. A mold plug for use in forming a relatively large opening in a slab casting of artificial stone or the like, comprising a plate-like body having a peripheral surface substantially conforming in contour to the opening desired to be formed in the casting, a flexible band removably mounted on said surface, and a pair of suction cups on the bottom side of said body mounted on pins extending through said body and slideable axially therein.

4. A mold plug for use in forming a relatively large opening in a slab casting of artificial stone or the like, comprising a plate-like flexible body having a continuous resiliently flexible peripheral wall of plastic with a thin, single, terminal edge portion disposed in a common plane, said body and said wall being unitary, a valved fitting in said body providing a passage communicating with opposite sides of the body for use in establishing and maintaining a vacuum beneath said body to hold the same in place.

References Cited UNITED STATES PATENTS 2,694,847 11/1954 Christiansen 25ll8 X 2,728,127 12/1955 Armstrong 249183 X 3,004,320 10/1961 Beckman 249l77 X 3,101,566 8/1963 Stiller 248206 X 3,148,433 9/1964 Carriker 25ll8 X J. SPENCER OVERHOLSER, Primary Examiner.

E. MAR, Assistant Examiner. 

1. A MOLD PLUG FOR USE IN FORMING A RELATIVELY LARGE OPENING IN A SLAB CASTING OF ARTIFICIAL STONE OR THE LIKE, COMPRISING A PLATE-LIKE BODY HAVING A PERIPHERAL SURFACE SUBSTANTIALLY CONFORMING IN CONTOUR TO THE OPENING DESIRED TO BE FORMED IN THE CASTING, AND MEANS FOR DETACHABLY FASTENING SAID BODY TO THE WALL OF THE MOLD INCLUDING AT LEAST ONE RESILIENT SUCTION CUP ON THE BOTTOM SIDE OF SAID BODY, AND AN ELEMENT EXTENDING THROUGH SAID BODY FROM TOP TO BOTTOM AND BEING MOVABLE RELATIVE TO THE BODY AND SUPPORTING SAID CUP AT ITS LOWER END. 